Process of reducing organic keto compounds



Patented Dec. .9, 1930 NIT STATES PATENT" OFFICE EDUABDOF'LUDWIGSHITFENT-ON-THE-RHINE, GERMANY, ASSIGNOR TO GEN- ERALANILIN-EWOR KQ INQ, OF. NEW YORK, N. Y., A CORPORATION 0E DELAWARE PROCESS OFREDUCING ORGANIC KETO COMPOUNDS have found that vat dyestuffs and alsoother organic substances, which'contain reducible carbonyl or quinonegroups, like obtained directly inx adry, or nearly dry,

state, It is therefore possible to subject the reduction products, inthe reduction mixture itself, to *furtherreactions in which the presenceof wateris injurious or undesirable. In particular, the products canbetransformed directly into esters by treatment with acylating agents,such as chlorsulfonic acid or esters' of same, phosphorous oxychlorid,acetic anhydride and the like. In this way, not only is the worksimplified, but the products are also oftenobtained in a purer state andin higher yield than by other methods. In some cases the acylating agentmay even be added already in the course of the reduction.

The reduction products may also be first isolated, for example byfiltering orotherwise removing the products, which usually separate cut,in crystallineform, during the reaction or on cooling or diluting thereaction mixture, or by distilling off the bases and the diluentemployed, if such be added, preferablyfunder diminishedpressure. Theresult ing leuco-compounds may then be converted, for example,"int'o thesulfuric esters, by treat ment, according to the U; S. Patent No.1,448,251; with a mixture of dimethylanlline, chlorbenzene andchlorsulfonic acid.

For'zthe reduction, the sulfurous acid or formic acid, or both, theemployment of which in the free state affords the advantage that noinorganic salts are brought into the reduction mixture, mayalso beapplied partly in a combined condition, for example as dry sodiumbisulphite with formic acid or ammoniumor metal-formates.

, N 'nrewrn Application filed Ma a 1927, Serial No. 192,796, and inGermany June 24, 1926.

Example 1 13 parts of sulfurous acid are introduced into 150 partsofpyridine, followed, at ore dinary temperature, by 30 parts of 5.5.7.7-tetrabromindigo and 3.5 parts of a 98 per cent solution of formic acid.The dyestufi is completely reduced in 20 minutes or thereabouts bywarming the mixture to from to C, accompanied by good stirring and thepassage of a non-oxidizing gas such as carbon dioxid or coal gas throughthe reaction mixture. On cooling the resulting golden yellow solution,the bulk of the leuco-compound separates out as yellow crystals. Thepyridine can be almost completely expelled from the solution bydistillation at about 40 C. under diminished pressure, the greenish-yeLlow :leuco-compound being left behind in a dry state.

Example 2 10 parts of 5.5'47/77 tetrabromindigo are reduced, at from 30to 40 C, in a mixture of parts of pyridine, 8 parts of sulfurous acidand3 parts of a 98 per cent formic acid solution." 20 parts ofchlorsulfonic'acid are then dropped slowly into the mixture at from 8 to12 C., whereby the hitherto golden-yellow reduction mixture acquires abluish color. The mixture is next warmed, the color again becomingyellow at about 45 C., and the temperature is maintained at 70 C. forabout half an hour, after which the mass is poured into cold water, themixture rendered alkaline with sodium carbonate or caustic-sodasolution, and the pyridine expelled by, distillation with steam. Theresulting sulfuric acid ester of the leuco-comi in of thioindigo arereduced, from tered solution, either by evaporation or: by

salting out with sodium or potassium chlorid.

If the 5.5.7 .7 -tetrabromindigo be replaced by parts of 5.5dib-1orhindigo, the I sulfuric acid ester; of the leucocompound of thisdyestufi? isobtained in a similar manner.

, mExample-g in p 10 to minutes, in a mixture of 70 parts of and 05 partof Water, the operation being carried out atfrom 70 to 75 C., in anatmosphere ofcarbon dipziid. Onlcool ing, the so.- lution deposits ampleamounts of pale, yel low needles of leuco-thioindigo If the ;mix

' ture be trcatedp at fromf10 to 12? (1., with an esterifying agentprepared from, parts of chlorsulfonic acid and 80 parts of pyridine in:the. cold, andis thenwarmed to toQ (1., for aboutan hour,.thefaintlyredsolu-I v tionbeing renderedalkaline and freed from" pyridineby distillation with steam, a nearlycolorless solution is obtained whichcontains the quantitatively formed I sulfuric acid ester Q l n hio o- ,lI to j V I Ewampl e a Y eparts of .ind igofare reduced in ahoutg 3O V-minutes, at from 40, to -C.,binfa mixture of 40 parts of pyridine, 10partsfof sulfui ous acid and L5 parts oi an per jcentiformic I acidsolution. The resulting indigo-white pasteis treated with amixture ofl5mparts 'of chlorsulfo'nic acid, or '15 parts of chlorsul-efonic-acid-methyl ester, and 50 parts of pyridine, and the mixture.through which carbon dioxid isslowly passed, is stirred at from 20toi309" C., until free leuco-compound can no' longer be detected. Afterrenderingthe solution I alkaline; the pyridine is, distilled offvwithsteam, and the small residual amount of indigo is removed byfiltration; The solution can be concentrated andsalted out, to recoverthe 'resultingesulfuric acid ester of the leuco nd g e o yield beingobtained. I z-Emamplefl I A inixture'of 5 parts of 5.5''.7.7"-tetrabromindigo, 40 parts of dimethyl'aniline, parts of 98 percent ethyl alcohol" andr2 .5 parts of 11185 per cent formic acidsolution are heated, under 'a reflux condenser, on the w aterbath,'sulfurous vacid being passed concurrently until reduction,recognized by the appearance of a pure yellow coloration, is complete.-The alcoholisfexpelled from the mixtureby distillation at from 309 to40 0., under reduced pressure, and a mixture of thel'euco compound oftetrabromindigo and dimethylaniline, with a faint bluish tinge, is

left. I I

v;dimethox L Y; mwmwunmmem r placed by 20 parts of aniline, a mixture of7 the leucocompound of tetrabromindigo and aniline will be left afterdistilling of! the alcohol; I I e in Eiwampled n ,7 4.5 parts of98percentfor1nic acid solution are dro "ridine an 10 parts ofsulfurouseacid,.at from 0 to 10 0. a current of dry carbon dioxid tureis thenraised to from 25f to 30fi fl', 'jwhereuponreductiomwith the formationof a ed into a mixture of 10 parts of 0 en" zanthrone, :80 parts of p7,:

red'so1uti 0rsu pens on, occurs-i 103m 15 dry pyridine, 10partsotsulfurous acid,"2{*being. passedfitheretfirough. The'tempempartsof-a 98 per cent formic acidsolution inu es; Amixtu e i 0pcr s ofpyridine and 20 parts oi 1clilorsulfonic-v acid 1s theni added fatfrorn5. w 15f;v C., andlthe whole is heated conc rto-35 G'. for two; hours;and

thr e, s; a ,recipitatd'f fromthe dark; redfiltered so ution, yconcentration, or 3 by,

L' lm X nre i 261'??? c sod um, p c u fh e .290 P ts Z Q amii'P SP I 5PP- form czacid luti n dfi s fmm n w emu is e e efr m 8 e-90?;C;inm e mp r 1 08 ,s eJiwQmP e by-ish i -l duction lwill be complete in 1 :from15* to 20 minutes, and the solution will deposit. indiv-j go-Ywhite'on'addition of 'water.

;' If the," digo beereplaced by other vat. dye- V stufi's, I such, for;example" as 5.5edich1ore d q lwne fi e n g s t e 1 1 c m: poundsiofsame' willbeiobtained;

What l claim isz an organ c compound containing a keto then foragfurthenhour 509 C. vThe red mixture isnpou-red onto ice,-. and afterbeing Ialine with caustic soda solution, ridine. by distillation ,1with,

I no -Pm w i wmpri es ubje in group, to I the, action, of sulfurousaeid, and

I formic c d, nt e p s n ct a Organic as b t st n i y in; the? s c of we-I; T: H. gr. 1 i I 2.-The;process which comprises subjecting anorganic. compound iconteiningeagketo group .to the-action T of,sulfurous" acid and formic acid in the 1 resence of; Inorganic Ibas'efand anqinert diliient, but {substantially in the absence'ofwater,1, i I

' 3. The process which comprises subjecting an organic compoundcontaining: a. skate group to the action of sulfurous acid andformic'facid in the presence ofIan-organic baseybut substantially in theabsenceoffwater, andltreating the reaction with an' acylating agent.

vat dyestufi's to the action of sulfurous acid and formic acid in thepresence of an organic base, but substantially inthe absence of Water. a

5. The process which comprises subjecting quinone compounds to theaction of sulfurous acid and formic acid in the presence of an organicbase, but substantially in the absence of Water.

In testimony whereof I have hereunto set my hand.

EDUARD MljNCI-I.

